Method and system for layerwise production of a tangible object

ABSTRACT

A method cycle of a method for layerwise production of a tangible object ( 5 ) comprises the steps of:—solidifying a predetermined area of a layer ( 10 ) of a liquid ( 3 ) when said liquid layer ( 10 ) is adjoining a construction shape, so as to obtain a solid layer ( 14 ) of the tangible object ( 5 );—separating said solid layer from said construction shape; and—moving, relative to one another, the separated solid layer and the construction shape to a predetermined position relative to one another for carrying out a successive such method cycle, so as to obtain a successive such solid layer adhered to the solid layer. For at least one of said method cycles, said solidifying and said separating are carried out such that solidifying of certain parts of the layer ( 14 ) takes place simultaneously with separating of other, already solidified parts of the layer.

FIELD AND BACKGROUND OF THE INVENTION

The invention relates to a method for layerwise production of a tangibleobject according to the preamble of claim 1. The invention also relatesto a system for layerwise production of a tangible object.

Such a method is known. For example it is known from DE10256672A1 thatthe liquid reservoir has a transparent bottom plate whose upper side hasa separation layer. In the space above the bottom plate there is acarrier plate which can be moved up and down. During its movement, thecarrier plate can reach positions ranging from under the liquid level toabove it. A firstly formed solid layer of the tangible object is adheredto the underside of the carrier plate by selectively solidifying theliquid. Consecutively formed solid layers are each adhered to apreviously formed solid layer, respectively.

Each time after solidification of a new layer, the carrier platetogether with the earlier solidified layers adhered thereon are movedupwards in order to separate the last formed solid layer from theseparation layer of the bottom plate. Each time after such separation,the separated solid layer is moved to a predetermined position at adistance from the separation layer of the bottom plate for letting theliquid flow-in between the separated solid layer and the separationlayer of the bottom plate. By solidifying a predetermined area of alayer containing the flown-in liquid, a successive solid layer of thetangible object is obtained.

A drawback of the known method is, that during each method cycle thetime required for said separation and for the liquid to flow-in betweenthe separated solid layer and the separation layer of the bottom plateis relatively long. This restricts the speed of the production process.

Note that this restriction in production speed is especially severe forobjects having strongly varying cross-sections. This is explained asfollows. The upward separation movement of the carrier plate requires anexternal force to be exerted on the carrier plate. This external forceresults in an increase of internal stresses in the tangible object beingproduced. If these stresses become too high, the object can deform,deteriorate or break. Hence, for the known method, the maximumpermissible internal stress level in the tangible object restricts themaximum permissible level of external forces to be applied, and hencerestricts the production speed. Since vertical tensile stresses inobjects with varying cross-sections can become locally very high, therestriction in production speed is especially severe for such objects.

SUMMARY OF THE INVENTION

It is an object of the invention to enable a faster production of atangible object.

Therefore, according to a first aspect of the invention, a methodaccording to claim 1 is provided.

In this method according to the first aspect of the invention, for atleast one of said method cycles, said solidifying and said separatingare carried out such that solidifying of certain parts of the layertakes place simultaneously with separating of other, already solidifiedparts of the layer. Favourable effects of such simultaneous solidifyingand separating are elucidated as follows.

At first, the simultaneous solidifying and separating provides a speedgain of the process in itself. That is, the start of separating a layerdoes not have to wait until all parts of the layer have been solidified.Hence, there is little or no downtime of the separating means. Also,there is little or no downtime of the solidifying means.

Secondly, the separating of the layer is carried out more gradually inthat it is performed part by part, instead of the whole layer at once.This means that, as compared to known methods, external forces to beexerted for the separation movement, and therefore the internal stressesin the tangible object, do not need to be that high anymore for a givenseparation speed. In fact, such external forces can be increasedrelative to known methods, without violating a maximum permissibleinternal stress level in the tangible object. In this respect, a furthergain in production speed can be obtained.

Furthermore, according to a second aspect of the invention, a systemaccording to claim 9 is provided.

Specific embodiments of the invention are set forth in the dependentclaims.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, aspects and embodiments of the invention will bedescribed, by way of example only, with reference to the drawings.

FIG. 1 schematically shows a sectional side view of an example of anembodiment of a system according to the invention.

FIG. 2 schematically shows a sectional side view of an example ofanother embodiment of a system according to the invention.

FIG. 3 schematically shows a sectional side view of an example of yetanother embodiment of a system according to the invention.

FIGS. 4A and 4B schematically show a fragmentary sectional side view ofan example of yet another embodiment of a system according to theinvention.

FIGS. 5A and 5B schematically show a fragmentary sectional side view ofan example of yet another embodiment of a system according to theinvention.

DETAILED DESCRIPTION

Each of the examples of FIGS. 1-5 relates to a system according to claim9 that can perform an example of a method according to claim 1. In therespective figures sometimes the same reference signs are used forsimilar or identical parts or aspects of the systems.

Hence, each of the examples of FIGS. 1-5 relates to a system forlayerwise production of a tangible object, the system comprising:

a liquid reservoir for containing a liquid therein;

a construction shape for being in contact with the liquid in the liquidreservoir;

solidifying means for solidifying a predetermined area of a layer of theliquid, said liquid layer adjoining the construction shape, so as toobtain a solid layer of the tangible object, the solid layer thus havinga predetermined shape;

separating means for separating said solid layer from said constructionshape;

moving means for moving, relative to one another, the separated solidlayer and the construction shape to a predetermined position relative toone another for similar solidifying a predetermined area of a successivesuch liquid layer containing liquid flown-in between the separated solidlayer and the construction shape, so as to obtain a successive suchsolid layer adhered to the solid layer;

wherein the system is arranged for carrying out said solidifying andsaid separating such that solidifying of certain parts of the layertakes place simultaneously with separating of other, already solidifiedparts of the layer.

In each of the examples of FIGS. 1-5 the tangible object is shown whilebeing produced. It may for example be a prototype or model of an articleof manufacture or other suitable type of object.

In each of the examples of FIGS. 1-5 the solidifying means can use anysuitable chemical or physical process to solidify the predetermined areaof the liquid layer. The solidifying means may for example initiate achemical reaction of a component in the liquid which results in a solidreaction product. For example, the liquid may be a liquid resin whichcan be cured by electro-magnetic radiation, for example a photo-polymerof which polymerisation can be activated by projecting light of asuitable wavelength. The liquid can be transformed into a solid by asuitable type of energy and the solidifying means may include a sourceof energy which can selectively provide the energy to the predeterminedarea. The source of energy may for example include a source ofelectro-magnetic radiation. The solidifying means may include a lightsource which can emit light which is projected onto the predeterminedarea of the liquid layer via a projection unit of the solidifying meansin a pattern corresponding to the desired shape and size of the solidlayer.

In each of the examples of FIGS. 1, 2 and 3 the construction shapecomprises a flexible layer having a liquid contacting side for being incontact with the liquid in the liquid reservoir, and the constructionshape is arranged for bending, in operation, the flexible layer suchthat time-dependently varying contacting parts of the liquid contactingside of the flexible layer are in contact with the liquid layer forsolidifying said certain parts of the layer, while time-dependentlyvarying other parts of the liquid contacting side of the flexible layerhave been separated from said other, already solidified parts of thelayer.

Such application of such flexible layer can easily and effectively beincorporated in many different methods and systems for layerwiseproduction of tangible objects.

Furthermore, in each of the examples of FIGS. 1, 2 and 3, theconstruction shape comprises guiding means arranged for being inpressing contact with a side of the flexible layer opposite to theliquid contacting side for defining the time-dependently varyingcontacting parts of the liquid contacting side of the flexible layer.

Such application of such guiding means is an easy and effective way ofcarrying out the bending of the flexible layer.

In the example of FIG. 1, the guiding means is arranged for realizingsaid pressing contact by means of sliding of the guiding means alongsaid opposite side of the flexible layer.

Such sliding contact allows for a large area of said pressing contact,which is for example favourable for keeping the time-dependently varyingcontacting parts of the liquid contacting side of the flexible layerflat in conditions when the liquid in the reservoir would exertrelatively large pressure on these contacting parts.

In the examples of FIGS. 2 and 3, the guiding means is arranged forrealizing said pressing contact by means of rolling of the guiding meansalong said opposite side of the flexible layer.

Such rolling contact reduces the wear of the flexible layer.

In the example of FIG. 2, said rolling of the guiding means is realizedat least in that the flexible layer is rollable in a closed loop aroundat least two rollers.

This allows for a compact way of realizing the construction shape withrolling guiding means.

In the example of FIG. 3, said rolling of the guiding means is realizedat east by means of a winding and rewinding mechanism for the flexiblelayer.

This allows for an alternative way of realizing the construction shapewith rolling guiding means.

In the examples of FIGS. 4A, 4B, 5A and 5B, said simultaneous takingplace of solidifying and of separating is realized in another way thanin the examples shown in FIGS. 1, 2 and 3. More in particular, for theembodiments of FIGS. 4A, 4B, 5A and 5B, said simultaneous taking placeof solidifying and of separating is realized in that a relative rotativemovement is performed between the construction shape and the objectunder construction.

Reference is now made to FIG. 1, which shows a system 1 according to theinvention.

The system 1 comprises a liquid reservoir 2 which, in the shown example,is filled with a liquid 3 upto a liquid level 4. The system 1 furthercomprises a construction shape 6 which is positioned below the liquidlevel 4 in the liquid reservoir 2. In the shown example the reservoir 2comprises a bottom platform 7 and the construction shape 6 comprises,located above platform 7, a flexible layer 8.

The system 1 further comprises solidifying means 9 for solidifying apredetermined area of a layer 10 of the liquid 3, said liquid layer 10adjoining the construction shape 6, so as to obtain a solid layer 14 ofthe tangible object 5, the solid layer thus having a predeterminedshape.

In the shown example, the solidifying means 9 is situated below thebottom platform 7. To enable the light or other radiation 15 of thesolidifying means 9 to enter the liquid reservoir 2, the bottom platform7 and the flexible layer 8 of the construction shape 6 are transparentto the radiation 15.

As will be explained somewhat further below, the system 1 furthercomprises separating means for separating said solid layer 14 from saidconstruction shape 6.

The system 1 further comprises moving means for moving, relative to oneanother, the separated solid layer 14 and the construction shape 6 to apredetermined position relative to one another for similar solidifying apredetermined area of a successive such liquid layer containing liquid 3flown-inbetween the separated solid layer 14 and the construction shape6, so as to obtain a successive such solid layer adhered to the solidlayer 14.

In the shown example, the moving means comprises a carrier plate 20located above the construction shape 6. As indicated by double-arrow 25in FIG. 1, the carrier plate 20 is movable up and down relative to theconstruction shape 6 by the action of a carrier plate actuator 21.During its movement, the carrier plate 20 can reach positions rangingfrom under the liquid level 4 to above it. A firstly formed solid layer24 of the tangible object 5 is adhered to the underside of the carrierplate 20. Consecutively formed solid layers 34 are each adhered to apreviously formed solid layer, respectively.

Each time after solidification and separation of a new layer, thecarrier plate together with the solidified layers adhered thereon aremoved upwards. Hence, the method for layerwise production of a tangibleobject is a cyclic method, wherein the described steps of solidifying,separating and positioning together are comprised in a single cycle ofthe method.

The system is arranged for carrying out said solidifying and saidseparating such that solidifying of certain parts of the layer takesplace simultaneously with separating of other, already solidified partsof the layer. This is explained as follows.

The separating means for separating said layer 14 from said constructionshape 6 simultaneously with the solidifying of a predetermined area ofthe layer 14 is explained as follows.

The flexible layer 8 has a liquid contacting side for being in contactwith the liquid 3. Inbetween the flexible layer 8 on the one hand andthe bottom platform 7 on the other hand, there is situated a guidingmeans 81 of the construction shape 6. Upper parts in FIG. 1 of theguiding means 81 are in pressing contact with a side of the flexiblelayer opposite to the liquid contacting side. In the shown example, saidpressing contact is realized by means of sliding of the guiding meansalong said opposite side of the flexible layer. Lower parts in FIG. 1 ofthe guiding means 81 are in rolling contact with a side of the bottomplatform 7 by means of rollers 80. In the shown example, on the oppositeside of the platform 7 also the solidifying means 9 are in rollingcontact with the platform 7 via similar such rollers 80. Both theguiding means 81 and the solidifying means 9 are synchronously movablerelative to the platform 7 via these rollers 80 in either or bothdirections indicated by double arrow 73 in FIG. 1.

In the shown example, the platform 7 is transparent to the radiation 15,while the guiding means 81 contains a passageway for the radiation 15.Alternatively, the guiding means 81 can also be transparent to theradiation 15 instead of having a passageway therefor.

As an example it is now assumed that, in the course of time during theperforming of a method cycle, the guiding means 81 and the solidifyingmeans 9 are synchronously moving in the right-hand direction of arrow 73in FIG. 1. Then, at the instantaneous moment in time shown in FIG. 1,there are contacting parts of the liquid contacting side of the flexiblelayer 8 which are in contact with the layer 10 for solidifying certainparts of the layer 10. During the movement of the guiding means 81 andthe solidifying means 9, these contacting parts are time-dependentlyvarying. In FIG. 1 on the left-hand side of these contacting parts thereare time-dependently varying other parts of the liquid contacting sideof the flexible layer 8 which have been separated from said other,already solidified parts of the layer 10. The liquid 3 is able to flowinbetween said other parts of the liquid contacting side of the flexiblelayer 8 and said other, already solidified parts of the layer 10. Thisis possible because the flexible layer 8 is bended by the movement ofthe guiding means 81 in the direction 73.

Reference is now made to FIGS. 2 and 3 which show examples of otherembodiments of a system for layerwise production of a tangible object 5.

A difference with the embodiment of FIG. 1 is that for the embodimentsof FIGS. 2 and 3 an upper layer 14, instead of a lower layer 14, of anobject 5 under production is solidified during each method cycle. Thecarrier plate 20 is situated under the object under production, insteadof above it, while the solidifying means 9 is situated above the objectunder production, instead of under it. In FIGS. 2 and 3 the carrierplate 20 is movable up and down in directions 125 by the action of anactuator 21 which extends through the bottom of the liquid reservoir 2of the system. It is remarked that it is not essential that the actuatorextends through a bottom of the liquid reservoir. Instead, differentother types of actuators are possible, for example an actuator extendingfrom the carrier plate in upwards direction until above the liquid level4.

In the examples of FIGS. 2 and 3 the flexible layer is indicated byreference numeral 108.

A further difference with the embodiment of FIG. 1 is that for theembodiments of FIGS. 2 and 3 a different guiding means is applied. Thatis, the guiding means in FIGS. 2 and 3 comprises rollers 85 forrealizing said pressing contact by means of rolling (instead of sliding)of the guiding means along said opposite side of the flexible layer 108.

A difference between the examples of FIGS. 2 and 3 is that for theexample of FIG. 2 said rolling of the guiding means is realized at leastin that the flexible layer 108 is rollable in a closed loop around atleast two rollers 85, while for the example of FIG. 3 said rolling ofthe guiding means is realized at least by means of a winding andrewinding mechanism for the flexible layer 108. The winding andrewinding mechanism of FIG. 3 comprises two winding and rewindingrollers 88.

For the embodiments of FIGS. 2 and 3, the assembly comprising theflexible layer 108, the rollers and the solidifying means aresynchronously movable relative to the reservoir 2 in either or bothdirections indicated by double arrow 173. The necessary driving meansfor such movement are not shown in the drawings. During such movementthe flexible layer 108 is moving in one of the directions indicated bydouble arrow 174, such that the parts of the flexible layer 108 that arein contact with the layer 10 are not moving relative to the layer 10.

Note, that in the example of FIG. 1 the sliding of the guiding meansalong said opposite side of the flexible layer is applied for a systemin which a lower layer 14 of an object 5 under production is solidifiedduring each method cycle, while in the examples of FIGS. 2 and 3 therolling of the guiding means along said opposite side of the flexiblelayer is applied for a system in which an upper layer 14 of an object 5under production is solidified during each method cycle. However, it isremarked that the vice versa situation is also possible. That is, it isalso possible to apply rolling of the guiding means for a system inwhich a lower layer of an object under production is solidified duringeach method cycle, while it is also possible to apply sliding of theguiding means for a system in which an upper layer of an object underproduction is solidified during each method cycle.

Reference is now made to FIGS. 4A and 4B. These figures show a fragmentof a system 201 for layerwise production of a tangible object 5. Thesystem 201 comprises: a construction shape 206 having a liquidcontacting side 211 for being in contact with liquid 3 in a liquidreservoir of the system 201, as well as solidifying means 9 for emittingradiation 15. Reference numeral 214 denotes the last formed solid layerof the object 5. The construction shape 206 and the solid layer 214 havenonmatching shapes. In the embodiment shown in FIGS. 4A and 4B saidnonmatching shapes are realized in that the solid layer side 214 has anon-flat shape.

The solidification that the solid layer 214 has undergone, has beencarried out by moving the object 5 relative to the construction shape206 in a kind of rotative manner indicated by double arrow 275. Tofurther illustrate this, FIG. 4B shows a condition during said rotativemovement, in which condition the object 5 has an orientation relative tothe construction shape 206, which orientation differs from that of FIG.4A. In the course of time during such rotation, different parts of theliquid 3 between the solid layer side 270 and the contacting side 211are being solidified by exposing these parts to the radiation 15. Inthis way the solid layer 214 has been formed in the course of time.

For this embodiment, the application of the said nonmatching shapesresults in improved separation, since the liquid 3 will quickly fill upthe expanding interspace between the solid layer 214 and theconstruction shape 206.

Reference is now made to FIGS. 5A and 5B. These figures show a fragmentof a system 301 for layerwise production of a tangible object 5. Thesystem 301 comprises: a construction shape 306 having a liquidcontacting side 311 for being in contact with liquid 3 in a liquidreservoir of the system 301, as well as solidifying means 9 for emittingradiation 15. Reference numeral 314 denotes the last formed solid layerof the object 5. The construction shape 306 and the solid layer 314 havenonmatching shapes. In the embodiment shown in FIGS. 5A and 5B saidnonmatching shapes are realized in that the liquid contacting side 311has a non-flat shape.

The solidification that the solid layer 314 has undergone, has beencarried out by moving the construction shape 306 relative to the object5 in a kind of rotative manner indicated by double arrow 375. To furtherillustrate this, FIG. 5B shows a condition during said rotativemovement, in which condition the object 5 has an orientation relative tothe construction shape 306, which orientation differs from that of FIG.5A. In the course of time during such rotation, different parts of theliquid 3 between the solid layer side 370 and the contacting side 311are being solidified by exposing these parts to the radiation 15. Inthis way the solid layer 314 has been formed in the course of time.

Again, also for this embodiment, the application of the said nonmatchingshapes results in improved separation, since the liquid 3 will quicklyfill up the expanding interspace between the solid layer 314 and theconstruction shape 306.

In the foregoing specification, the invention has been described withreference to specific examples of embodiments of the invention. It will,however, be evident that various modifications and changes may be madetherein without departing from the broader spirit and scope of theinvention as set forth in the appended claims. For example, the liquidreservoir may be higher or lower than shown in the FIG. 1. Furthermore,the object may have any suitable size and shape. Also, the invention isnot limited to physical devices or units implemented in non-programmablehardware but can also be applied in programmable devices or units ableto perform the desired device functions by operating in accordance withsuitable program code. Furthermore, the devices may be physicallydistributed over a number of apparatuses, while functionally operatingas a single device. Also, devices functionally forming separate devicesmay be integrated in a single physical device. However, othermodifications, variations and alternatives are also possible. Thespecifications and drawings are, accordingly, to be regarded in anillustrative rather than in a restrictive sense.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word ‘comprising’ does notexclude the presence of other elements or steps than those listed in aclaim. Furthermore, the words ‘a’ and ‘an’ shall not be construed aslimited to ‘only one’, but instead are used to mean ‘at least one’, anddo not exclude a plurality. The mere fact that certain measures arerecited in mutually different claims does not indicate that acombination of these measures cannot be used to advantage.

1. A method for layerwise production of a tangible object (5), themethod comprising: providing a liquid reservoir (2) containing a liquid(3); providing a construction shape (6; 206; 306); and repeatedlyperforming method cycles, each method cycle comprising the steps of:solidifying a predetermined area of a layer (10) of the liquid (3) whensaid liquid layer (10) is adjoining the construction shape, so as toobtain a solid layer (14; 214; 314) of the tangible object (5), thesolid layer thus having a predetermined shape; separating said solidlayer from said construction shape; and moving, relative to one another,the separated solid layer and the construction shape to a predeterminedposition relative to one another for carrying out a successive suchmethod cycle for similar solidifying a predetermined area of asuccessive such liquid layer containing liquid (3) flown-in between theseparated solid layer (14; 214; 314) and the construction shape (6; 206;306), so as to obtain a successive such solid layer adhered to the solidlayer; characterized in that for at least one of said method cycles,said solidifying and said separating are carried out such thatsolidifying of certain parts of the layer (14; 214; 314) takes placesimultaneously with separating of other, already solidified parts of thelayer.
 2. A method according to claim 1, wherein the construction shapecomprises a flexible layer (8; 108) having a liquid contacting side andwherein said simultaneous taking place of solidifying and of separatingis realized in that said liquid contacting side is brought in contactwith the liquid (3) in the liquid reservoir (2) and the flexible layeris bent such that time-dependently varying contacting parts of theliquid contacting side of the flexible layer (8; 108) are in contactwith the liquid layer (10) for solidifying said certain parts of thelayer (10), while time-dependently varying other parts of the liquidcontacting side of the flexible layer (8; 108) have been separated fromsaid other, already solidified parts of the layer (10).
 3. A methodaccording to claim 2, wherein the construction shape (6) comprisesguiding means (81; 85; 87) and wherein the guiding means are brought inpressing contact with the side of the flexible layer (8; 108) oppositeto the liquid contacting side for defining the time-dependently varyingcontacting parts of the liquid contacting side of the flexible layer. 4.A method according to claim 3, wherein said pressing contact is realizedby means of sliding of the guiding means (81) along said opposite sideof the flexible layer (8).
 5. A method according to claim 3, whereinsaid pressing contact is realized by means of rolling of the guidingmeans (85; 87) along said opposite side of the flexible layer (108). 6.A method according to claim 5, wherein said rolling of the guiding means(85) is realized at least in that the flexible layer (108) is rolling ina closed loop around at least two rollers (85).
 7. A method according toclaim 5, wherein said rolling of the guiding means (87) is realized atleast in that the flexible layer (108) is winded and rewinded by meansof a winding and rewinding mechanism (88).
 8. A method according toclaim 1, wherein said simultaneous taking place of solidifying and ofseparating is realized in that a relative rotative movement is performedbetween the construction shape (206; 306) and the object (5) underconstruction. 9-15. (canceled)